But how did word spread so quickly to cause the police needing to be called in to certain stores? Quite simple – social media and mobile phones, in particular SMS. But there was one other element to this: the messages on Twitter, Facebook and blogs as well as the mobile text messages all came from people that the receiver knew – in other words a trusted network.

And that’s what made the difference. If the message ‘Tesco giving away beer at £11′ had been from strangers or companies, then it would have been treated sceptically or as spam (and ignored). But because it came from people that the end receiver (in this case, you and I) had previous, trusted relationships with, we knew it was legit. And many people jumped in the car.

The next time someone asks what’s the power of digital communications, get them to call their local Tesco and ask how much beer they had on their shelves left at end of business on June 1 2010.

Why you want to be part of or create a trusted network

If people trust you, they will believe you and have a deeper relationship with you. If you are a company or brand, that makes them more likely to want to spend time and money with you. If you’re part of a trusted network you have credibility.

How to become part of a trusted network

Engage with people on their terms and platforms, don’t sell to them all the time online. Be helpful, be conversational. Talk with them, not to them. And always remember the 7:2:1 rule of engagement – only one in every ten of your posts should be a blatant product sell.